Hello, it sounds like there might be a couple of potential issues with your Apollo SA4705-701APO smoke detector. Firstly, the flashing red LED indicates a trouble condition, which could be due to various reasons such as power supply issues, sensor contamination, or internal faults. To troubleshoot, start by checking the power supply to ensure it’s stable and within the required voltage range for the detector. Next, inspect the detector for any signs of dust or debris that might be interfering with the sensor’s operation. If the detector is clean and properly powered, but still not functioning correctly, it may be a sign of internal faults requiring professional servicing or replacement. Remember, always follow safety procedures and consult the manufacturer’s manual for specific troubleshooting steps.